For the production of plastic containers, in particular plastic tanks, it is known to employ the method of thermoforming and, correspondingly, thermoform pressing. Further, what may be referred to as double-ply thermoforming or double-mould thermoforming is known, in which plastic half-shells are simultaneously thermoformed in two moulds and are subsequently welded to one another in the hot and pasty state at their margins to form a hollow body.
A method for the double-ply thermoforming of plastic fuel tanks and an apparatus for the production of plastic fuel tanks are known from WO Patent Publication No. WO 2004/062889 A1, two heated plastic plies being moved independently of one another to a thermoforming station, the individual plastic plies being lowered into a first and a second shaping die, the first and the second die being arranged laterally next to one another, each plastic ply being thermoformed into a shell, and one of the shaping dies, together with the thermoformed shell, being overturned and arranged above the other die, and, finally, overlapping sealing regions of the shells being pressed together and being thermally fused.
European Patent Publication No. EP 1 314 528 A2 discloses a thermoforming press for the production of formed parts, comprising a mould supporting table, which is suspended on a frame beneath a forming-die subassembly, and a pair of moulds which are mounted side to side on the mould supporting table, means being provided for pivoting the said mould supporting table along an arcuate reciprocating path and for alternately aligning and registering one of the said moulds and then the other of the said moulds with the forming-die subassembly.